This invention relates generally to gas turbine engines, and more specifically to a system configured to start the gas turbine engine and also configured to generate electrical power.
At least some known gas turbine engines used with aircraft include a core engine having, in serial flow arrangement, a compressor which compresses airflow entering the engine, a combustor which burns a mixture of fuel and air, and low and high pressure turbines which extract energy from airflow discharged from the combustor to generate thrust.
As aircraft accessory power demands have increased, there also has been an increased need to run the gas turbine engines at idle speeds that may be higher than other engines not subjected to increased power demands. More specifically, increasing the gas turbine engine idle speed enables the increased power demands to be met without sacrificing compressor stall margins. However, the increased idle speed may also generate thrust levels for the engine which are higher than desired for both flight idle decent operations and/or during ground idle operations. Over time, continued operation with increased thrust levels during such idle operations may increase maintenance costs and the increased fuel flow requirements may also increase aircraft operating expenses.